Many water use applications like swimming pools, spas, hot tubs, cooling towers, process water, and the like, require a constant residual of biocide chemicals to control bacterial and algal populations, in order to have sanitary water safe for the users, operators, and service personnel. Typical organisms that will grow in the water in such systems include Chlorococcum, Chlorella, Cledaphora, Microcystis, Oscilratoris, Spirosyra, Olaothrisx, Vanetteria, and Aspergilles flavus. The prevention or inhibition of growth of these micro-organisms in water systems has been a problem.
It is customary to treat water systems with one or more sanitizers and/or sanitizer/oxidizer combinations to control the growth of micro-organisms. The sanitizers most commonly used to control the growth of micro-organisms are chemicals that generate hypochlorite or hypobromite species when dissolved in water. There are many hypochlorite generating chemicals, with the more common ones being chlorine gas, alkali metal hypochlorites such as sodium hypochlorite, alkaline earth metal hypochlorites such as calcium hypochlorite and lithium hypochlorite, halogenated hydantoins and chlorinated isocyanuric acid derivatives such as sodium or potassium dichloro-s-triazinetrione.
The most common sanitizers that are used in applications that directly contact people (swimmers, waders, or bathers, etc) are oxidizing sanitizers that release hypochlorous acid (chlorine) into the water. It is common practice to periodically “shock” or “oxidize” the water by adding a significant amount of an oxidizing chemical to water to destroy inorganic and organic contaminants. Shock products are largely solid products. In some cases, chlorine- or halogen-releasing products are periodically used to oxidize contaminants, shock and kill bacteria and algae.
It is highly desirable to have multi-functional oxidizer or shock products for use in water treatment applications. Examples of such patented technology relating to mixtures of a chlorine source, a non-halogen oxidizer source, and other additives are Pat. Nos. 5,478,482, 5,514,287, and 5,670,059. The research disclosed in these patents show a synergy between sodium dipersulfate and sodium dichloro-s-triazinetrione.
Prior art teaches that the oxidation performance of sodium dipersulfate compound is greatly dependent on temperature. It is more effective when the temperature is at or above 60° C. and experience a decreased reactivity at the lower temperatures.
Although, the prior patent indicates that blends of sodium dipersulfate and dichloro-s-triazinetrione have superior oxidization properties when compared to the individual components, it is desirable to further improve the oxidation properties of sodium dipersulfate in the formulations with dichloro-s-triazinetrione especially at ambient temperatures.
Since the swimming pool water temperature is generally ambient, a large quantity of peroxy compound will have to be used to provide the desired benefits. The dependence of peroxy compound on temperature and concentration is practically and economically significant. As a consequence, there is much interest in catalyzing or activating peroxy compounds, which will increase the oxidation performance of these compounds by allowing them to be effective at ambient temperatures. Such substances are generally referred to in this art as catalysts or peroxy compound catalysts or activators.
U.S. Pat. No. 3,702,298, issued to Zsoidos et al. on Nov. 7, 1972, teaches a method for treating swimming pools with a combination of a peroxy salt, such as peroxymonosulfuric acid and copper salt. However, no prior art teaches the use of two transition metal salts in combination to activate sodium dipersulfate oxidation.
It is, therefore, an object of this invention to provide an improved peroxy salts based formulation catalyzed by two transition metal for treatment of water system. This formulation may or may not additionally contain chlorine releasing chemicals, a clarifier and a biocide.